Snohomish County Prosecutor Mark Roe speaks for Initiative 594 with King County Prosecutor Dan Satterburg in the background.

The Ballmers gave $125,000 apiece, swelling their total contributions to $600,000.

The pro-594 campaign reports more than $1.1 million in cash on hand, according to its filings with the state Public Disclosure Commission.

The alliance was formed, largely by faith leaders, after the December 2012, massacre of 20 first graders in Newtown, Connecticut.

After the Washington Legislature failed to act, supporters collected signatures to put on the ballot a statewide initiative that would close the “gun show loophole.”

I-594 would require criminal background checks for those purchasing firearms at gun shows and online. A rival, gun lobby-backed measure, I-591, would block background checks. It would forbid Washington from enacting any regulation not a part of federal law.

The pro-594 forces collected well over $1 million in pledges during a luncheon at the Westin last June. The money has very gradually found its way into Public Disclosure Commission reports, as if the campaign is holding back to see what the gun lobby does.

Not much, so far. The Protect Our Gun Rights group has raised $1.1 million, and has about $300,000 in cash on hand. Its latest chunk of cash was an Aug. 7 donation of $250,000 from Washington Arms Collectors.

The National Rifle Association has registered a group with the wordy name of National Rifle Association of America Washingtonians Opposed to Initiative 594. It is a shell campaign so far, having raised just $25,000 and spent $17,000.

Especially after a recent gaffe by its state lobbyist — he likened the criminal background check measure to life in Germany under the Nazis — the NRA has to make a decision on whether to come into the Washington campaign in a big way.

It spent in the seven figures 17 years ago to defeat a measure to require trigger locks on weapons stored at home together with a mandatory firearms safety course by new firearms purchasers.

This year, it faces a professionally run campaign with deep pockets, with big name backers in law enforcement — the prosecutors of King and Snohomish Counties — plus a substantial lead in the polls.